Apart from the fact that I disagree that temporal segregation on the O-Train is anything akin to conditions on USRC, VIA Rail doesn't operate UPX.
Here is what I wrote:
[These would actually be excellent for the Weston Corridor in lieu of ordering more of the problematic Sharyos, if TC allows operation as with the O-Train (freight temporal separation)] I stand by that claim, and obviously, since I presume you've been reading my posts, UPX isn't owned or operated by VIA. I never stated otherwise. The Sharyos are problematic just on price alone, let alone inflexible future operation on that line. There's also no-one doing follow-on orders for them, or likely to be doing so. So it's time for Metrolinx to look at what will fit with their future electrification plans on the Weston Corridor, and order and operate stock in such a way (which might require blockaded track in lieu of relaxation of present TC regs) as to allow a much more economical and *prolific* way to utilize that corrridor, and be completely forward compatible.
If you have a solution that satisfies that without a change in regs, and is *affordable*, then by all means, share it. The status quo is not acceptable.
Britain explored inserting one or more EMU coaches in the middle of a Class 220 DMU, to give it dual-mode capability. The option was discarded as the economics didn't work out. Class 220's don't meet TC standards, but the theory might be adaptable to some other model of vehicle, and VIA might see different economics.
I'm not an electrical engineer, but I gather the power delivery from a diesel-generator set is apparently quite different from the power delivered from overhead catenary, so it's not as simple as having electrical traction motors and just throwing a switch to select the power supply.
Indeed, they did, and other nations have not only tested it, they sell them! Three last time I checked. Of course none meeting FRA regs. But as some posters alluded, it's the *concept* that is the value in this discussion.
I am a technologist, involved in transformer design, specifically toroidal, and to cut a long discussion short, there's a whole other aspect not mentioned, and that's *phase*. Pantograph pickup by it's very nature *almost* precludes multi-phase (I am aware of one exception, but it was, not surprisingly, problematic), and what you need to drive modern AC motors is multi-phase, three being the minimum and by far, the most popular. And the bogies used on electric locos and diesel electric can be identical, which lends themselves exquisitely to triple phase power xmssn through connecting cables via the coaches from one end to the other to distribute the tractive effort. This is done with 25kV AC along trainsets from the pantograph(s) to the transformer(s) often in other coaches. Other than the nature of the induced losses, lower voltage triple is vastly safer and able to neutralize most of it's induced field by being 'balanced'. And somewhat redundant, as in a failed leg of the three, as long as the vehicle remains in motion, can keep the vehicle going at a 30% reduction of power until safely stopping. (Starting is the problem with a 'broken leg' but that's another topic)
For now, I offer this reference:
http://ecmweb.com/basics/using-single-phase-transformers-create-3-phase-systems
This subject will come up in some form or another, even if it's HEP, but I suspect you're going to hear a lot more about 'distributed traction' than you now do. Keep "Cow and Calf" in mind on this...some posters are alluding to it. And with a double prime motored diesel loco, that becomes even *more* relevant, as per economy and 'greeness'.
The main issue is one of voltages. 25kV AC from the overhead (with fairly large range of actually voltages), versus the fairly clean and even ~2400V AC from the alternator attached to each engine. The transformers and equipment that you need for each are quite different.
Yes and no. Doubtless, you can't work with 25kV AC as is...albeit as much as it's "the work of Satan" to me, (for a variety or reasons, not the least the shock hazards of even computer 'switching power supplies') transformers *can* now be rendered redundant. Witness UHV DC transmission lines as in Quebec. It's all solid state switching. It has to be! It's DC! Xfrmrs won't work...(note: This is handled by extremely high voltage solid state inverters 'reconstituting' the power back to AC. See:
https://library.e.abb.com/public/9e16e26d65ab7339c12572fe004deb21/22-27 2M733_ENG72dpi.pdf)
Whatever, without doubt, in the motor world, medium voltage (in the range you mention 2.4kV ) is far more more practical to work with, insulation easy to address, winding numbers easy to work with, and *efficiencies* keep growing ever higher.
What this discussion might evolve to, rather than the specifics of the latest proven technologies elsewhere comes down to, is *is VIA going to settle for yesterday's technology?*. Given triple traction current fed through the coaches to distribute either to the coaches themselves as EMU, or to the traction motors on bogies either end, but a distributed weight electric loco one end, diesel the other, there's a *drastically reduced need* to hedge bets on tomorrow's technology. For a start, only a very few runs will need an electric loco, so why 'lock-in' a design when it can be satisfied in a *modular fashion* as needed? If you are dragging that electric loco around, at least utilize the weight on the bogies powered from the other end. And by not having one loco to do both, you're also distributing the *weight* to either end, for safety, and for vastly reduced track and equipment wear. *IF* a bi-modal loco is at either end, then it still makes perfect sense to use as little in the way of prime-movers to affect the speed and performance desired, so again, that 'traction power bus' from end-to-end makes perfect sense.
The real question remains 'through coach triple phase traction current'. Once that is satisfied, the locos can be added in as per spec needed, including asymmetric mode at each end if needed . Until that time, the cabling is in place in the coach-set for feed-through traction current. And including refurbished perfectly good locos in a new lifetime, able to be cascaded out later when surpassed with the latest needed spec.
Edit to Add: Still Googling to find examples of a 'power bus' carried through a coach consist, but here's the simplest denominator of the concept as to distributed tractive effort from a 'mother' prime mover and a 'calf':
[...]
A slug is used to increase adhesive weight, allowing full power to be applied at a lower speed, thus allowing a higher maximum tractive effort. They are often used in low-speed operations such as
switching operations in
yards. At low speeds, a
diesel-electric locomotive prime mover is capable of producing more electricity than its traction motors can use effectively. Extra power would simply cause the wheels to slip and possibly overheat the traction motors. A slug increases the number of traction motors available to the locomotive, increasing both the pulling and braking power. In addition the load on each traction motor is reduced, which helps prevent overheating from excess current. Slugs typically carry ballast to increase their weight and improve traction. Large blocks of
concrete are frequently used for this purpose, substituting for the weight of the now-absent prime mover.
Slugs can be built new or converted from existing locomotives. Conversion has enjoyed popularity as a way to reuse otherwise obsolete locomotives, especially those with worn-out diesels and good traction motors.[...]
https://en.wikipedia.org/wiki/Slug_(railroad)#External_links
With the latest in micro-controllers and IGBT/SCR/Triac controllers, this can be taken to a much more pliable degree in controlling not only braking and acceleration, but to optimize the traction needs of each loco to keep as steady a stress on the couplings as possible while still maximizing acceleration/braking when needed.
Still digging for better reference...;
